RU2288827C1 - Method for preparing tube edges for welding - Google Patents

Abstract

FIELD: processes for welding thick-wall tubes without using additives, namely method for preparing tube edges for electron-beam welding.

SUBSTANCE: end of one of welded tubes is faced by means of cutter by angle 90° relative to its axis. End of other tube is worked by angle 90° relative to its axis inside tube and in upper portion of worked end annular protrusion is remained. Thickness and length values of said protrusion are no more than 4 mm. Technological groove is formed by means of cutter under said annular protrusion; depth and width of said groove are no more than 1 mm. With use of rolling out roller annular protrusion is bent outside by angle 45 - 90° relative to tube axis. Bent protrusion is turned for imparting to its cross section shape of isosceles triangle or isosceles trapezium or rectangle for forming protruded additive. In end of tube under protruded additive cylindrical cavity is turned with inner diameter equal to outer diameter of end of first tube. Said cavity is turned by depth equal to half of base of cross section of protruded additive.

EFFECT: simplified, reduced-cost process for assembling tubes for welding due to automatic centering of tubes at assembling.

3 cl, 6 dwg, 1 ex

Description

The invention relates to welding predominantly thick-walled pipes without the use of an additive, and more particularly, to a method for preparing pipe edges for electron beam welding by performing a filler protrusion on the pipe welded edge due to cold deformation on the lathe of the pipe end with a rolled roller.

The well-known "Method of preparing the edges of products mainly of pipes for welding", through which grooves of a triangular shape are machined at the pipe end, and then using a rolling roller on a lathe by successive cold deformation of triangular protrusions form a filler protrusion of a triangular shape on the outer edge (see a. S. USSR No. 831463 from 05.23.81). According to the known method, by cold compression at the end of the tube of annular protrusions of a triangular shape using a rolling roller, it is difficult to obtain an annular protrusion at the upper edge of the end of the end with a sufficient metal volume for non-splicing welding, since during the rolling process, the metal at the end of the pipe quickly becomes stuck and subsequently practically ceases to deform plastic, as a result of which the filler ring protrusion is small and its volume for welding pipes with a wall thickness of more than 3 mm is not enough to produce a weld equal to the main pipe wall.

Another disadvantage of this method is the difficulty of assembling the ends of the pipes for welding.

The exact combination of the welded ends of the pipes requires the use of a special centering device equipped with a mechanism for preloading the welded ends, which complicates and increases the cost of preparing the pipes for welding.

The problem to which the claimed invention is directed is to develop a method for preparing pipe edges for welding, in which due to cold deformation of the pipe ends with a rolling roller, it would be possible to obtain a filler protrusion of practically any volume required by the welding technology depending on the wall thickness of the pipes being welded with the formation minimal metal hardening at the pipe end and small efforts on the rolling roller.

The technical result obtained by solving the problem is that in the known method, the process of successively flattening the protrusions at the end of the pipe by a roll roller is replaced by the bending of one large annular protrusion made in the upper part of the end of the pipe. At the same time, the efforts on the rolling roller in the process of bending the annular protrusion to the outside of the pipe require several times less effort than in the process of flattening the protrusion, which allows the pipe ends to be welded to turners of average skill.

In addition, the inventive method of preparing the edges of the pipes for welding allows you to give the welded ends such a complementary shape that when joining the pipes for welding, they automatically center them, which simplifies and reduces the cost of pipe assembly for welding, because It does not require careful coaxial joining of the ends without a gap, and this, in turn, ensures the quality of welding and its reproducibility, which does not depend on the qualifications of the welder.

The specified technical result is achieved in that in the method of preparing pipe edges for welding, including turning and cold deformation of the pipe end with the formation of a filler protrusion on its upper edge, the end of one of the pipes being welded is cut with a cutter at an angle of 90 ° to its axis, and the end of the second the pipes are processed from the inside at 90 °, leaving an annular protrusion with a thickness and a length of not more than 4 mm in the upper part of the end face, then this annular protrusion is bent outward at an angle of 45 to 90 ° with respect to the pipe axis with a rolled roller, and bent protrusion eat through, giving it a cross-sectional shape of the protrusion of the filler in the form of an isosceles triangle or isosceles trapezium or rectangle, and then a projection end of a filler eat through a cylindrical cavity with an inner diameter equal to the outer diameter of the end of the first pipe;

- in addition, at the end of the pipe under the annular protrusion before its bending, a technological groove is made by the cutter with a depth and width of not more than 1 mm;

- in addition, the cylindrical cavity of the second pipe is pierced to a depth equal to half the base of the cross section of the filler protrusion.

The inventive method of preparing pipe edges for welding allows you to replace the energy-intensive process of roller rolling of the end by sequentially flattening several annular protrusions at the end of the pipe by the process of bending to the outside of the pipe one sufficiently large annular protrusion. In this process, the protrusion metal does not work for compression, but mainly for bending and tension, which is much more economical in terms of energy costs, because In this process, there is practically no hardening process, which limits the plastic flow of metal, which is necessary for the formation of the filler protrusion of the required volume, necessary for welding without filing the filler in the weld zone.

To achieve this, the claimed method provides for a groove of the end from the inside to a depth of not more than 4 mm, leaving at the top of the end of the end of the annular protrusion not more than 4 mm thick, which, with the help of a rolling roller, bends the pipe walls outward at an angle in the range from 45 to 90 °. To facilitate the bending of the annular protrusion and better formation of the future filler protrusion from it, a technological groove is pierced under the annular protrusion with a depth and width of not more than 1 mm.

This technological groove allows you to move the base of the bent annular protrusion from the future end of the pipe, which, in turn, simplifies the formation of the future filler protrusion.

To simplify the alignment of the pipes to be welded together and to install the smooth end of the pipe to be welded, strictly under the axial line of the filler protrusion, the annular cavity is pumped to a depth equal to half the base of the cross section of the filler protrusion, which ensures guaranteed fusion of the pipes simultaneously with the melting of the filler protrusion, forming an even-flow welded joint due to metal filler ledge.

The method is performed in the following sequence.

First, the smooth end face of one pipe is pierced at 90 ° to its axis, as shown in FIG. 1, and then the end of the second pipe is partially pierced, as shown in FIG. 2, leaving an annular protrusion of no more than 4 mm in height and thickness in the upper part of the end face. The dimensions of the annular protrusion depend on the thickness of the pipe wall and the required size of the protrusion for welding without additives. After receiving the protrusion, it is bent upwards by an angle of 45 to 90 ° with the help of a rolling roller installed in the tool holder of the lathe, depending on the desired shape of the filler protrusion. To facilitate bending and better formation of a future filler protrusion from the bent annular protrusion, an annular groove is pierced under the annular protrusion with a depth and width of not more than 1 mm, as shown in FIG. 2. To obtain, for example, a filler protrusion in the form of a triangle, the annular protrusion 3 at the end of the pipe 2 is bent by 60 ° with the help of a rolling roller relative to the axis of the pipe, as shown in FIG. 3. After this operation, the end face and the bent annular protrusion are turned to form a filler protrusion 4 of a triangular shape and an annular cavity 5 with a diameter equal to the outer diameter of the end face of the first pipe 1, as shown in FIG. 4.

At the same time, the depth of the annular cavity is equal to half the base of the filler protrusion, after which the pipes are joined for welding without filler, as shown in Fig.5.

Figure 6 shows the joint after the formation of the weld 6.

Execution example

The edges of the pipes with a diameter of 90 × 5 mm of zirconium alloy were prepared for welding by an electron beam without feeding filler wire into the welding zone.

The end of one pipe was trimmed at 90 ° to the axis of the pipe, and the end of the second pipe was partially machined, leaving an annular protrusion 2.5 mm thick and 3 mm high at the top of the end. A technological groove 1 mm deep and 0.5 mm wide was machined under the protrusion.

After that, the annular end face of the second pipe was bent 60 ° from the axis with the help of a roll roller and formed from it by the method of turning the filler protrusion of a triangular shape with a triangle base equal to 2.5 ± 0.1 mm. Under the annular filler protrusion, an annular cavity was machined under the outer diameter of the end of the first pipe, the groove depth was 1.2 ± 0.1 mm.

The ends of the pipes to be welded were degreased and assembled for welding in the vacuum chamber of the electron-beam installation for welding pipes from active metals.

The ends of the pipes were squeezed with an ordinary screed in the form of a rod and flanges with holes for the screed with nuts.

Claims (3)

1. A method of preparing pipe edges for welding, including turning and cold deformation of the pipe end with the formation of a filler protrusion on its upper edge, characterized in that the end of one of the pipes to be welded is treated with a cutter at an angle of 90 ° to its axis, and the end of the second pipe is processed from the inside, at an angle of 90 ° to its axis, and leave an annular protrusion at the top of the end face, with a thickness and length of not more than 4 mm, then this annular protrusion is bent outward at an angle of 45 to 90 ° with respect to the pipe axis with a rolled roller, and the resulting the blunt is pierced and given in cross section the shape of the filler protrusion in the form of an isosceles triangle, or isosceles trapezoid, or rectangle, after which a cylindrical cavity with an inner diameter equal to the outer diameter of the end of the first pipe is pumped at the end of the second pipe under the filler protrusion. 2. The method according to claim 1, characterized in that at the end of the second pipe under the annular protrusion before its bending, a technological groove is made by a cutter with a depth and width of not more than 1 mm. 3. The method according to claim 1, characterized in that the cylindrical cavity of the second pipe is pierced to a depth equal to half the base of the cross section of the filler protrusion.

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